Would switching a larger capacitor in parallel with C3 allow for an LFO mode?

Yes, but that is a very sensitive part of the circuit. (The cap is already being tapped by two buffers). I think it might screw up the VCO tuning, so I'd advise against it. The VCO does in fact go subsonic anyway.

Quote:

If I left out the sine circuit, am I correct to assume that the Pulse output circuit could be connected to the saw output instead?

That would work. But if you listen to Scott's first recording on his Web site, I don't think you'll want to leave out the sine. I thought it was best part of his sample!

Quote:

Would a 1M pot work for the Rampoid skew control (R53)?

Yes. Keep the leads direct and to the point, though, since that represents a greater impedance.

Sure, go ahead and post your artwork here. That would be a real time-saving aid for the rest of the gang. Keep Scott posted as well; he'd probably want to include links to it in his write-up.

And thanks!

Thomas Henry

:o Otay! :salut: Thank you greatly Thomas and again, as well as for the VCO itself! Just from listening to Scott's audio from it, I fully agree with others that this guy, is going to be a hit! :)

Now - as to how I lay things out for PCBs ... (this one being a little more difficult so far around the first TL074, being single sided) ... wont look pretty. :o But if portions of it may assist someone else in doing a much neater / tidier version, then I'm all for that as well. :)Last edited by Rykhaard on Thu Mar 17, 2011 2:30 am; edited 1 time in total

Sure, go ahead and post your artwork here. That would be a real time-saving aid for the rest of the gang. Keep Scott posted as well; he'd probably want to include links to it in his write-up.

And thanks!

Thomas Henry

Now - as to how I lay things out for PCBs ... (this one being a little more difficult so far around the first TL074, being single sided) ... wont look pretty. But if portions of it may assist someone else in doing a much neater / tidier version, then I'm all for that as well.

K. My single sided PCB layout for the CD4046 1V/Oct. VCO, is completed. I still have to double verify it though before I post it's artwork here, with many great thanks and appreciation to Thomas, for his permission.

As with all of my PCBs, it may be considered ugly to many, but all of the components are labelled (in copper), except for a small # of the trimmer's names. (Their values are there.)

I'll verify the layout on lunch at work today, making any required corrections after work (including addition of the PCB's power input capacitors.) Once that's done, I'll post it to this thread for everyone to gander at. It may also be modified at will. I know others who are more familiar with layout rulings etc. that I'm unaware of, would do things differently. Once it's confirmed as correct at least, it'll give me the ability to make a bunch of Thomas's VCOs for myself.

This circuit took a little longer than most do. That's otay though. I verified it at work; found bugs; cleared them up and well ... there're more errors to find yet, apparently. I've pulled the err'd PCB to find and repair the errors.Last edited by Rykhaard on Thu Mar 17, 2011 2:34 am; edited 3 times in total

Thanks Thomas for once again going where few dare to venture!!!
and thanks for sharing the layout Ryk
maybe its just me but the rampoid pad looks pretty close to the ground trace, no doubt it will test my P'n'P skill!

Thanks Thomas for once again going where few dare to venture!!!
and thanks for sharing the layout Ryk
maybe its just me but the rampoid pad looks pretty close to the ground trace, no doubt it will test my P'n'P skill!

Thanks for making mention of that Andrew! A LOT of stuff in there is closer than I liked, but I were trying to get away from as many jumpers as I could, juggling everything.
Even though I've printed (PnP) 4 off to cook for myself, I'm going to do another check of it. If there're changes I'll hopefully be able to replace the above one with the new one.

Coming over from the lunetta forum, the 4046 caught my eye. I now see this is a toally different beast, and Im liking what I see. This could very well be my first actual VCO.

Thanks thomas henry, this looks and sounds great!

Great work on the pcb ryk, must have been hard cramming it onto this single sided board. With my lack of experience on making pcb's, I guess I'll wait for the finalized version.

keep up the good work _________________There he goes. One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.
Hunter S. Thompsonmoviesnoise

i really hope you don't mind, but i converted your neat pcb for pnp, as i'm keen to try this one out, it still might be too funky for some, but i guess it goes for this one, just want to give it a try, i might make a proper pcb with power connectors if i've got one going, but i thought i'll share this, it's your work after all, i just cleaned it in vain so one can try it. Thank you Thomas, thank you Ryk! It will be next to my 566 vco's.

also, im really looking forward to the vcf Thomas and Scott been teasing us here... Any info on that? And there's also another cmos vco? 4069?

i really hope you don't mind, but i converted your neat pcb for pnp, as i'm keen to try this one out, it still might be too funky for some, but i guess it goes for this one, just want to give it a try, i might make a proper pcb with power connectors if i've got one going, but i thought i'll share this, it's your work after all, i just cleaned it in vain so one can try it. Thank you Thomas, thank you Ryk! It will be next to my 566 vco's.

also, im really looking forward to the vcf Thomas and Scott been teasing us here... Any info on that? And there's also another cmos vco? 4069?

róbert

Whoa! That must have taken you a heck of a long time for editing! I don't mind at all! With Thomas's permission coming to me without my asking, I'm completely open to anyone changing it, in whichever way.

My only question: do you have a silk layer to show all of the values everywhere? (Maybe that's why mine looks so crowded, in comparison to yours, which looks so beautifully neat and tidy!

NOTE TO PNP USERS: (as I'm one of them as well.) If you'd like the PNP layout for printing, let me know and I'll post it here as well. You could always just reverse the image I had posted above, anyways. So, that may not matter. (Ahhh. But it will - the silkscreen layouts would have to be removed. Doh, on my part.
Anyhoo - lemme know if anyone wishes for the reversed output of it then, or, the original Express PCB file itself. I can mail it to you. )

I am impressed with the layout. It looks nice and tight. Nice work on doing it on a single side. Very cool for the PCB DIY crowd.

PS: Your MC14046 chips should be arriving soon man !

Much thank yous Bill! I haven't thought it were the neatest looking but as I've previously explained ...

Here's to major hoping that others can use it and that others DO (use SOME PCB layout, anyways.)
This circuit to me, with the sounds from it that Scott had done, is one beautiful answer for LOW COST VCOs, with a great amount of sonic capability!

And many thank yous for those chips coming! I have a PnP done for 4 boards. If all come out well - there's twice my # of VCOs as soon as they're built / tuned!

Scott Stites will be testing some RCA chips soon. I have shipped him 5 to run the experiment. The longer the list of chip manufacturers gets, the more options for folks here in our forum. Thanks Scott

I've built the core of it on vero, and using an MC14046 I was able to tune it over 5 octaves without too much trouble. I did try it with a TI CD4046 as well and like Scott I couldn't even get it to do 1 octave.
If it's Ok with everyone, I'd be happy to post a layout once I've built the rest of it and tidied it up a bit.

A quick question for anyone who's built it, do the trimmers for the wave shaper sections need to be multiturn or are single turn Ok?

If it's Ok with everyone, I'd be happy to post a layout once I've built the rest of it and tidied it up a bit.

yes please!
It looks like a nice and compact build, and with the veroboard this is going to be very cheap, good job _________________There he goes. One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.
Hunter S. Thompsonmoviesnoise

Thought that i would chuck in my progress on the X4046. I started a PCB before Rykhaard's came out... I have finished stuffing it but have yet to test it. I checked in a couple of additions in an extra sync mode which makes use of the Phase Decriminator that was unused otherwise. It has required the addition of a 4093 and an opamp for the filter (probably overkill for the filter) but I was interested to see how it works. I now think that I should have gone further and added some dividers to sync to octaves etc. I have given some thought to hacking in a PSoC 8 pin chip to do this... I have been fighting with a Moog 921 VCO clone and it makes use of an analog multiplier to provide sync so I was intersted to see how the 4046 will work. Not as well I suspect as the phase descrimination is in the digital domain and I'm not sure that you are going to get local maxima at some of the common ratio's... Will let you know how it goes! Thanks to Thomas for another very clever adaption on an Oscillator Chip!

so i decided to add two 4046 VCOs to my new cabinet. i started to populate the two left prototype VCO core PCBs. they output triangle and saw only.
i plan to build one saw/tri VCO and one full blown VCO (requires additional wave shaper PCB).
below my panel sketch for the full blown one (the pushbutton will have a built-in LED, the legend will change to AC only then):

Well my PCB worked OK -- apart from a missing resistor and a tiny short, which took a little while to find. I used an NXP (Phillips) 4046 and all seems well. Got the expected shapes after a little bit of tweaking. The triangle and sawtooth are a little hot being about +- 5.6V -- I am thinking about changing the feedback resistors slightly. Still need to trim the V/octave controls but I have misplaced my temco's... Also using the PLL discriminator for the extra sync mode still needs some more thought...

Hopefully will be able to tune this tomorrow after a rummage in the shed for the tempco's and post some graphs. I have a Fairchild 4046 as well so will try that for academic interest.

Only the tuning trimmers need be multiturn. The waveforms are easy to tweak with ordinary trimmers.

Thanks for confirming that.

Just thought I post a picture of the completed board. It's a bit of a mess because it's built on 2 pieces of vero but it all works great
The layout will be neater and use less insulated jumpers, I've just got to correct a couple of errors, generally tidy it up and re draw the expo converter because I used a different version to the original. Hopefully it will be ready sometime next week.

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.